Import ASEG-GDF2

Use the Database > Import > ASEG-GDF > Import GDF menu option (IMPASEG GX) to import ASEG-GDF2 data.

Import GDF dialog options

ASEG-GDF2 DEFN file

Select the ASEG-GDF2 header file (.dfn) containing the data formats.

If no DEFN file is specified, the GX will search for a .dfn file with the same name and location as the data file. If a data file is also not specified, the file indicated by the DEFN entry in the provided template file will be used.

See the Application Notes below for more information.

Script Parameter: IMPASEG.DEFN

ASEG-GDF2 data file

Select the ASEG-GDF2 input data file (.dat).

If no data file is specified, the GX will search for a .dat file with the same name and location as the DEFN file. If a DEFN file is also not specified, the file indicated by the DATA entry in the provided template file will be used.

See the Application Notes below for more information.

Script Parameter: IMPASEG.DATA

ASEG-GDF2 description file (optional)

Select the description file (.des, or .txt). The ASEG-GDF2 description file is an ASCII text file with no preset format, except that it contains the identifier "COMM" on every line. This parameter is optional.

Script Parameter: IMPASEG.DES

Flight line channel name

Defaults to "FLTLINE" initially. Subsequently, it displays the channel name specified in the most recent IMPASEG GX execution.

If the input flight line channel name does not match the entry in the DEFN file and no template file is specified, the name from the DEFN file will be used for the imported flight channel.
If no flight line channel is specified in the DEFN file, the flight line channel name field may be left blank in the dialog. This will cause all the data to be imported into a single line (L0) in the database.

Script Parameter: IMPASEG.FLC

ASEG-GDF2 template file

Specify the import template file (the .I4 extension is assumed). If not specified, either the DEFN file or the data file must be specified, and all the channels will be imported with their original names.

If the FLC entry in the template file does not match the entry in the DEFN file, an error will be prompted, and the import will fail.

Script Parameter: IMPASEG.TEMPLATE

ASEG-GDF2 projection file (optional)

Select the ASEG-GDF2 projection file (.prj) that contains the projection parameters. This parameter is optional.

Script Parameter: IMPASEG.PROJ

X channel to associate with projection

Specify a channel to be associated with the projection. The channel must be one of the channels in the DEFN file.

Script Parameter: IMPASEG.XCH

Y channel to associate with projection

Specify an additional channel to be associated with the projection. The channel must be one of the channels in the DEFN file.

Script Parameter: IMPASEG.YCH

Use fiducial channel

By default, the import does not check for the fiducial channel in the input data file. Select Yes from the drop-down list if you want to use the Fiducial field in the data file as the database fiducial channel, if available.

Script Parameter: IMPASEG.FIDUCIAL [0 - No; 1 - Yes]

Application Notes

Data can now be imported directly into a database using the IMPASEG GX, without needing a pre-existing template. However, you must specify at least one of the data or DEFN file names. If either the data or DEFN file is specified, the other is assumed to have the same name with the appropriate extension (i.e., either .dat or .dfn) and be located in the same directory.

The ASEG-GDF2 specification states that "An ASAEG-GDF2 data exchange has a minimum of four files." In practice, as few as two files may be used:

  • The data definition file (.dfn)

  • The data file (.dat)

The text description of the data and survey (.des) is often omitted.

Capturing the coordinate system information on import:

  • If coordinate system and map datum transform information is included in a separate PRJ (.prj)/MET (.met) file, its format must be described by PROJ and TRNS records in the DEFN (.dfn) file in order to capture it.
  • If a PRJ/MET file is not available, but the coordinate system and map datum transform information is included in the PROJ and TRNS records in the DEFN file, it will be captured.
  • If the coordinate system and map datum transform information is included in both a PRJ/MET file and the DEFN file, the information in the PRJ/MET file will take precedence.

    • Import Templates

    The import of ASEG-GDF2 data can be customized by creating an import template file (with the default extension .I4). This is an ASCII file that specifies the data channels you want to import and the database channels where you want to place the data. The SCANASEG GX can be used to scan a specified ASEG-GDF2 DEFN file and create a default import template that will import all data contained in the data file. Alternatively, if no template is specified when using the IMPASEG GX, a template is automatically created during the import, with the same name as the data file and the .i4 extension. This template can be edited to import a subset of channels or rename channels during import.

    Example of an ASEG-GDF2 import template:

    [IMPORT ASEG-GDF2]

    DEFN BOOTHILL.dfn

    DATA BOOTHILL.dat

    FLC FLTLINE

    IMPORT FLIGHT,FLIGHT,SHORT

    IMPORT DATE,DATE,LONG

    IMPORT TIME,TIME,FLOAT

    IMPORT FIDUCIAL,FIDUCIAL,FLOAT

    IMPORT ALTITUDE,ALTITUDE,FLOAT

    IMPORT TMAGRAW,TMAGRAW,FLOAT

    ALIAS L20440,L20440

    ALIAS L20450,L20450

    The template file is searched for the line [IMPORT ASEG-GDF2], and the IMPORT and ALIAS lines that follow are scanned to determine the data to be imported and the channels in which to place the data. You may add any comment lines before the [IMPORT ASEG-GDF2] line.

    DEFN syntax:

    DEFN file_name

    Where file_name is the name of the ASEG-GDF2 DEFN file to import.

    DATA syntax:

    DATA file_name

    Where file_name is the name of the ASEG-GDF2 data file to import.

    FLC syntax:

    FLC flight_line_channel

    Where flight_line_channel is the name of the ASEG-GDF2 channel containing the flight line information.  

    IMPORT syntax:

    IMPORT name, channel, type

    Where:

    • name is the name used in the ASEG-GDF2 DEFN file to indicate the data name.

    • channel is a mapping to the channel that will be created in the database.

    • type (one of BYTE, UBYTE, SHORT, LONG, FLOAT or DOUBLE) should correspond to the type in the DEFN file.  

    ALIAS syntax:

    ALIAS aseg_line_name, new_line_name

    As the ASEG-GDF2 lines are imported, if a line-channel already exists in the database, it will be replaced. The ALIAS statement in the import template can be used to rename ASEG-GDF2 data file lines during import. If the new_line_name is blank, the line will not be imported.

    If ALIAS is used, ALL lines contained in the ASEG-GDF2 file must be defined by an ALIAS line in the same order that the lines appear in the file. The SCANASEG GX can be used to construct a default template that includes ALIAS lines for all lines of a file. This file can be edited as required by the system.

    For example, if a file contains line L90, two sections of line L100, and a tie line L30, the following ALIAS lines can be used to import the data into properly named lines:

    ALIAS L90,L90

    ALIAS L100,L100.0

    ALIAS L100,L100.1

    ALIAS L30,T30

    Setting Coordinate Systems

    If the Specify coordinate system on import setting is set to "Yes" in the General Settings, and no coordinate system is defined for the current X and Y channels, Set Coordinate System will be called to set the projection on the X and Y.

    See Also: